ADJUSTING THE AIR VALVE GAP
The engine will make excess noise if the gap is too large in the air valve. If the gap is too
small valve operation will be hindered which could result in valve malfunction and failure.
Therefore, the air valve gap must be checked periodically.
The gap of the air valve should be inspected and adjusted when the engine is cold by a
qualified motorcycle technician at a service center:
1. Remove the caps of the central hole and the top hole (the ignition timing observation
hole) in the left crankcase cover.
2. Remove the caps of the two air valves on the cylinder head.
3. Insert the “T” key into the central hole of the crankcase cover, jam it against the nut of the
flying wheel and then turn the flying wheel clockwise until the engraved “T” mark on the
flying wheel aligns with the engraved line on the top of the crankcase cover. Swing the
rocking arm slightly. A loose rocking arm (which indicates the existence of clearance)
shows that the piston is in the upper stop position of the compressing stroke, where the
valve can be adjusted. A tight rocking arm means that the piston is in the lower stop
position of the compressing stroke. In this case, continuously turn the “T” key clockwise
for 360 degrees until the alignment of those engraved marks, where the valve can be
adjusted. Afterwards, check the valve gap by inserting a feeler in between the valve
adjusting screw and the end of the valve.
The specified air valve gap: 0.05mm for the intake and exhaust valves respectively.
